Choose a bit made for the material and the required hole diameter. A mixed set is useful when you drill wood, masonry and metal. A focused set is easier to check when one task matters most. Our three examples below show the difference between a mixed household kit and a metric HSS set. We have reviewed manufacturer specifications, not tested cutting speed, life or accuracy.
The set count is not the number of drill bits. Screwdriver bits and other accessories contribute to the stated 33- and 109-piece totals. Check the exact contents before comparing value. Confirm the hole diameter in a fixing, plug or fitting instruction before selecting any bit. Our fractional drill-bit size chart gives exact inch-to-mm conversions, but a conversion cannot tell you the right pilot size for every screw.
Which drill-bit type fits each material?
Match the bit type to wood, masonry or metal before comparing brands. The Bosch mixed kit separates HSS-R metal bits, masonry bits and wood bits. Trend's seven-piece metric HSS set is specified for metal, plastic and timber. It is not listed as a masonry set. These are manufacturer descriptions, not results from our own drilling.
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| Job | Bit to look for | Check before buying |
|---|---|---|
| Timber hole | Wood bit or a bit the maker specifies for timber | Diameter, length and whether the required finish calls for a brad point or another profile |
| Masonry fixing | Masonry bit | Plug or anchor maker's stated hole diameter and the wall material |
| Metal or plastic | HSS bit specified for the material | Diameter, workpiece material, drilling method and maker's guidance |
The table is a selection checklist. Follow the instructions for the drill, bit and fixing. A multipurpose kit does not make each included bit suitable for every surface.
Which UK drill-bit sets illustrate the main choices?
The Bosch X-Line 33-piece set covers three drilling materials; the Trend SNAP/D/SET/2 concentrates on seven metric HSS diameters. The DeWalt DT0109-QZ is a larger mixed accessory set. Count the named drill bits rather than using the total accessory count as a proxy for coverage.
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| Exact set | Drill-bit contents stated by maker | Useful for | Manufacturer source |
|---|---|---|---|
| Bosch DIY X-Line 33-piece, 2 607 019 325 | 7 HSS-R metal bits Ø2–5 mm; 5 masonry bits Ø4–8 mm; 6 wood bits Ø3–8 mm | A compact mixed-material kit | Bosch UK listing |
| DeWalt DT0109-QZ, 109-piece | 13 metal bits Ø1.5–6.5 mm; 5 masonry bits Ø3, 5.5, 6, 8 and 10 mm | A mixed accessory case with a wider stated metal-bit range | DeWalt UK listing |
| Trend SNAP/D/SET/2 | 7 metric HSS bits Ø1–7 mm with 1/4-inch hex shanks | Metric drilling in the maker's stated metal, plastic and timber applications | Trend UK listing |
The DeWalt page's introduction mentions brad-point bits, but its displayed component breakdown does not give a clear wood-bit count. We therefore do not present a wood range for that set. The published ranges describe the named kit versions rechecked on 3 October 2026; inspect the current box contents and product code before ordering. We have not compared prices or drilling performance. We verified a new UK Amazon offer for the Trend SNAP/D/SET/2 set on that date; offers can change.
What size drill bit should you use for a screw or wall plug?
Use the diameter specified for the fixing or hardware. A No. 6 screw designation alone does not identify a universal pilot bit. Timber type, screw design and whether a clearance hole is needed change the job. A wall plug or anchor may give a required masonry hole diameter on its packaging.
Our fixing hole and screw-size finder shows the maker-stated drill diameter, minimum hole depth and screw range for four exact fischer DuoPower pack numbers. Check your substrate and packet article number before using a row.
For an imperial instruction, multiply inches by 25.4 to obtain millimetres. NIST defines one inch as exactly 25.4 mm. For example, 1/4 inch is exactly 6.35 mm. A nominal 6 mm bit is therefore not an exact 1/4-inch substitute. Use the drill-bit size reference and CSV for all 1/64-inch steps through 1/2 inch.
How should you compare a drill-bit set before buying?
Compare the required material, diameter, bit length and shank with your actual jobs. Note whether a case's headline count includes screwdriver bits. Confirm the drill accepts the shank and that the bit's intended use matches the drill mode and material. A seven-bit set can be a better match for seven specific metal holes than a larger case with many driving accessories.
For a repeatable purchase check, write down the three most common holes you expect to make. Record each material, diameter and required depth. Then check the maker's component list against those holes. If the list is ambiguous, ask the retailer or manufacturer for the exact contents instead of assuming an advertised piece count covers the task.
How did we research these examples?
We rechecked the three linked UK manufacturer listings and the NIST conversion definition on 3 October 2026. We also matched the Trend SNAP/D/SET/2 set to Amazon UK ASIN B00N7QRXL8 in a browser and confirmed a new offer with UK delivery. This is a specification comparison. We did not buy the sets, drill test holes, measure tolerances, or establish bit lifespan. Product contents and stock can change. Recheck the exact model and maker page before purchase.